Re: cherry-pick very slow on big repository

From: Elijah Newren <newren@gmail.com>
Date: Nov 10, 2017, 17:37 UTC
Message-ID: <CABPp-BH4LLzeJjE5cvwWQJ8xTj3m9oC-41Tu8BM8c7R0gQTjWw@mail.gmail.com>
In-Reply-To: <alpine.DEB.2.00.1711101436270.2391@ds9.cixit.se>

Interesting timing. I have some performance patches specifically developed because rename detection during merges made a small cherry-pick in a large repo rather slow...in my case, I dropped the time for the cherry pick by a factor of about 30 (no guarantees you'll see the same; it's very history-specific). I was just about to start sending my three series of patches, the performance one being the third...

On Fri, Nov 10, 2017 at 6:05 AM, Peter Krefting <peter@softwolves.pp.se> wrote:

Show 29 quoted lines

> Derrick Stolee:
>
>> Git is spending time detecting renames, which implies you probably renamed
>> a folder or added and deleted a large number of files. This rename detection
>> is quadratic (# adds times # deletes).
>
>
> Yes, a couple of directories with a lot of template files have been renamed
> (and some removed, some added) between the current development branch and
> this old maintenance branch. I get the "Performing inexact rename detection"
> a lot when merging changes in the other direction.
>
> However, none of them applies to these particular commits, which only
> touches files that are in the exact same location on both branches.
>
>> You can remove this rename detection by running your cherry-pick with `git
>> -c diff.renameLimit=1 cherry-pick ...`
>
>
> That didn't work, actually it failed to finish with this setting in effect,
> it hangs in such a way that I can't stop it with Ctrl+C (neither when
> running from the command line, nor when running inside gdb). It didn't
> finish in the 20 minutes I gave it.
>
> I also tried with diff.renames=false, which also seemed to fail.
>
>
> --
> \\// Peter - http://www.softwolves.pp.se/